The invention relates to a rotary tool, particularly to a drill, with the features of the preamble of claim 1, and to a cutting head for such a rotary tool.
A rotary tool of this type is known for example from WO 2008/072840 A2 or from the applications PCT/EP2015/056288 or DE 10 2015 211744.8 by the applicant, which were not published at the time of the application.
The rotary tool is what is known as a modular rotary tool which extends in an axial direction along an axis of rotation and comprises two coupling parts, namely a carrier and a cutting head. The cutting head is interchangeably attached to the carrier. For this purpose, the carrier generally comprises on its end surface two opposing fastening webs which are separated from each other by flutes and by means of which the pin receptacle is delimited. A coupling pin of the cutting head is inserted into this pin receptacle. This is carried out by rotating the cutting head around the axis of rotation relative to the carrier. During this rotation, a clamping connection between the cutting head and the carrier is typically formed so that the two coupling parts are held together in a clamping manner. In particular, no additional fastening media such as screws or the like are arranged therein. The clamping attachment takes place between the outer shell surfaces of the coupling pin and the inner shell surfaces of the pin receptacle.
Furthermore, surfaces corresponding to one another are formed for transmitting a torque from the carrier to the cutting head. These torque transfer surfaces are hereinafter referred to in short as torque surfaces.
Modular rotary tools can be differentiated into two different types. In a first type, which can be gleaned for example from WO 2008/072840 A2, the torque surfaces extend radially outward up to an outermost circumference of the cutting head, which is also referred to as a drill rear portion. According to a second variant, for example as is described in the two aforementioned unpublished applications, the torque surfaces are directly formed on the coupling pin as shell surfaces thereof which interact with corresponding inner shell surfaces of the fastening webs.
Both the torque surfaces and the clamping surfaces of the cutting head and the carrier are opposite one another in pairs in the coupled state, i.e. when the cutting head is inserted into the carrier. The clamping surfaces corresponding to one another then respectively produce a press fit.
In the aforementioned applications, in order to prevent a pulling-out in the axial direction, stop surfaces that extend approximately horizontally and that interact with the corresponding stop surfaces of the carrier are respectively formed on the coupling pin in order to thus ensure a positive locking (or securing) in the axial direction for the cutting head. This positive locking (or securing) prevents the cutting head from being pulled out of the carrier in the axial direction—for example, when pulling the rotary tool out of the drill hole after a drilling process.
In WO 2008/072840 A2, a circumferential groove in the manner of a piercing (or incision) is formed on the coupling pin in order to produce this axial pull-out protection. In a similar manner, in the two aforementioned applications unpublished at the time of the application the stop surfaces are also formed by being radially ground in in the manner of piercings (or incisions). This is associated with a certain effort, owing to the complex geometries of the cutting heads.